1. Field
The subject matter disclosed herein relates to receiving wireless signals transmitted from one or more communication systems such as, for example, one or more global navigation satellite systems.
2. Information
A satellite positioning system (SPS) may comprise a system of transmitters positioned to enable entities to determine their location on the Earth based, at least in part, on signals received from the transmitters. Such a transmitter typically transmits a signal marked with a repeating pseudo-random noise (PN) code of a set number of chips and may be located on ground based control stations, user equipment and/or space vehicles. In a particular example, such transmitters may be located on Earth orbiting satellites. For example, a satellite in a constellation of a Global Navigation Satellite System (GNSS) such as Global Positioning System (GPS), Galileo, Glonass or Compass may transmit a signal marked with a PN code that is distinguishable from PN codes transmitted by other satellites in the constellation, (e.g., using different PN codes for each satellite as in GPS or using the same code on different frequencies as in Glonass). To estimate a location at a receiver, a navigation system may determine pseudorange measurements to satellites “in view” of the receiver using well known techniques based, at least in part, on detections of PN codes in signals received from the satellites
FIG. 1 illustrates an application of an SPS system, whereby a mobile station (MS) 100 in a wireless communications system receives transmissions from satellites 102a, 102b, 102c, 102d in the line of sight to MS 100, and derives time measurements from four or more of the transmissions. MS 100 may provide such measurements to position determination entity (PDE) 104, which determines the position of the station from the measurements. Alternatively, the subscriber station 100 may determine its own position from this information.
Wireless communications system receivers or position location system receivers, such as, for example, mobile station 100 described above, may include multiple antennae or signals at several frequencies in some circumstances in an effort to improve performance. Signals received at different antennae or signals at different frequencies may undergo different paths and may therefore be unlikely to experience similar fading of other unfavorable conditions, for example. However, incorporating multiple antennae or signals at different frequencies into communications receivers may result in additional circuitry required to implement multiple receiver channels leading to increased costs and power consumption, for example.